Silicon-based transistors are well suited for low-voltage applications. But in high-voltage applications (e.g., greater than 100 V of supply voltage), the breakdown voltage of a silicon-based transistor increases, thereby causing its channel resistance to go up disproportionately. As a result, there is a large tradeoff in the BV*Ron figure-of-merit. Increasing the breakdown voltage of a silicon-based transistor also increases the transistor's device capacitances significantly, which generally slow down the transistor's switching efficiency.
To address these issues, a high-voltage device may be used in a cascode configuration with a silicon-based transistor. The high-voltage device can be a high electron mobility transistor (HEMT), such as a gallium-nitride (GaN) HEMT. Typically, a GaN HEMT includes a two-dimensional electron gas (2DEG) channel that provides a high breakdown voltage and enables ultra-high-power-density operations with low power loss. During switching operations, however, there may be excessive ringing between the silicon-based transistor and the high-voltage device. In order to suppress the ringing phenomenon, a ringing suppressor can be placed at the control gate of the high-voltage device.
While the ringing suppressor can suppress the ringing phenomenon, it will increase power loss and reduce switching efficiency of the cascode configuration. Thus, there is a need for a high-voltage switch with low power loss and high switching efficiency.